We propose a strategy for solving the three-dimensional x-ray crystallographic structure of the single strand DNA binding protein, the product of gene 32, of bacteriophage T4. The strategy currently includes proteolytically modifying the protein in order to obtain suitable crystals; it also will involve efforts to cocrystallize the protein with DNA oligomers. The T4 gene 32 protein is intimately involved in DNA replication, recombination, and repair. It also has an unusual mechanism of autoregulation: it is a translational repressor of its own synthesis. The three dimensional structure of the protein should provide a foundation for interpreting the wealth of biochemical and genetic data on its function; it is likely that this system will provide a prototype model for involvement of DNA binding proteins in nucleic acid metabolism and translational regulation in higher organisms.